I am looking at a custom ECU that supports the bosch fuel system and is able to convert to other types of fuel systems. I have a 2.3 8V engine. Tell me what you guys have done. The ECU should also be able to incorperate a turbo or supercharger.

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George Carstens

You do not want a custom ECU. What you need is a programable engine management system like the Haltech E6K, Electromotive TEC II or the ACCEL DFI gen 7. Or go crazy and get a Motec.

A programable system can control all of your motor's functions and can be programmed via laptop. When you change mods, add forced induction, etc. you just put it on a dyno and load a new program.

If you are anywhere near TX, call Norwood Autocraft at 972-831-8111 and tell them what you want to do. They can design and install whatever you need.

You might want to look into simple Digital Systems I am looking for something for my 2.3-16 and this appears to have everything at a reasonable price. I installed a supercharger and am trying a number of things to get my fuel management correct and I am about ready to replace it all (dump CIS). I will post what ever I do.

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Jim Villers
190SL, 230SL 5-speed, 95 E320 Wagon, 01 E320 Wagon, MGB, Boxster 'S', 190SL "Barn Find"

I can't wait to see what you do.

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George Carstens

Managing a blower motor should not be that difficult. If you give me some more info, perhaps I can help.

- does your ECU chase a lamda value?
- what kind of blower are you using?
- how much boost are you running (peak)?
- what size are the stock injectors?
- how much peak hp will you make at the crank?
- how are you pulling timing?

FastNSX ... I accept any help I can get. For background, read my two threads: "Supercharger Problems" and "Installing a supercharger on a 2.3-16". You can also see progress pictures.

In summary, I currently have the stock CIS injection system and stock ignition system (with R-16 removed). I have a fuel/air ratio gauge that indicates erratic mixture which varies from very lean to very rich. The supercharger is from a SLK 230 and I am targeting 5-7psi max.

I currently have a "power module" installed, which should increase the current to the EHA when in boost but the mixture under boost still does not appear to be predictable.

Bottom line is that I am going to replace it all and move to a modern engine management system with electronic controlled injectors. My immediate task is to fabricate a fuel rail and an adapter for a Ford Mustang throttle body.

More when it occurs.

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Jim Villers
190SL, 230SL 5-speed, 95 E320 Wagon, 01 E320 Wagon, MGB, Boxster 'S', 190SL "Barn Find"

If money is not a major issue, I would go with my original suggestion, which is to install a programmable system. An ACCEL DFI would do everything you need. If there is a dealer near you, you could probably get it installed and tuned for about $2K. It would solve all of the problems.

If that is too much, you have a couple of other options. I am not familiar with the ECU on that car, but if it chases a lambda value, you can take care of the fuel issue by adding a rising rate regulator (FMU). Paxton makes a good one, but there are several on the market. They increase the fuel pressure at a set ratio based on the boost. Most can be adjusted anywhere from 6:1 to 14:1. I would guess you would end up with something in the neighborhood of 8:1. They use a variety of springs and plates to vary the rate at which they increase fuel pressure. You just put the car on a dyno, do a pull and see how your A/F ratio changes with boost. Then you fit the parts that most closely match the fuel rate to the boost rate. The Kleeman kit uses this method.

Obviously, your fuel pump has to be able to deliever the necessary amount of fuel. If it does not, you can replace it with an aftermarket unit (Walbro, etc.) or use something like a Boost-A-Pump. Kenne Bell sells a nice boost-a-pump. It increases the voltage to the stock fuel pump at certain boost or rpm levels to increase the capacity. Neat trick.

Lastly, you need to figure out how to pull timing as boost increases. There are several gadgets that can do this. Any shop that deals in aftermarket forced induction can point you in the right direction. Almost all aftermarket blower and turbo kits come with something to do that. Off the top of my head, I think Split Second and MSD both make timing retard boxes.

A third fuel solution is possible if your blower setup has runner space between the compressor and the intake. If it does, you could also add an injector bung or two and control them with something like a Rebic 4. It is a couple hundred bucks and is easy to program. You simply run the rest of the fuel system normally and use the extra injector(s) to make up the difference required by the boost. Several blower kits use this method and it is fairly simple to do. I have a conceptual issue with it in that I like to deliver fuel through the stock injector locations, but I have seen it work very well. In fact, I just helped a guy do a twin-turbo NSX that way.

Hope this helps at least a little. Good luck.

Thanks for all of the good info ..... Three or four months ago I would have been interested in trying some of the alternatives that you mentioned. As it is, I have ordered a fully programmable ECU from SDS

It will fully manage fuel delivery and ignition timing. I will post my progress and experiences when they occur.

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Jim Villers
190SL, 230SL 5-speed, 95 E320 Wagon, 01 E320 Wagon, MGB, Boxster 'S', 190SL "Barn Find"

One more thing. You should do the math and make sure that at your target crank hp level and current fuel pressure, you are not exceeding 80% duty cycle on your injectors. If so, either bump the fuel pressure to compensate or go to bigger injectors. Increasing the fuel pressure is the easiest option and most injectors can take a significant increase in fuel pressure with complete realiability.

You can find the formulas for calculating duty cycles here:

http://www.rceng.com/technical.htm#WORKSHEET